The present invention relates to antennas and, in particular, to radio frequency antennas for transmitting and receiving radio frequency signals. Even more particularly, the present invention relates to a compact antenna which is provided for use in connection with a radio frequency controlled lighting control system. In particular, the present invention relates to an antenna which is provided on a lighting control device, for example, a light dimmer, and which receives and transmits radio frequency signals for controlling a lamp and communicating status of the lamp e.g., on, off and intensity level. The radio frequency signals are used to control from a remote location the status of the lamp connected to the light dimmer and also to provide information back to a master location concerning the status of the controlled lamp. The device at the master location may also employ the antenna according to the invention.
The invention also relates to a control device employing the antenna that can be mounted in a standard electrical wall box. In particular, the invention also relates to a local electrical control device capable of remotely controlling one or more electric lamps and adapted to be mounted in a standard electrical wall box and receiving and transmitting signals via the antenna. The invention further relates to a master control device capable of remotely controlling one or more electrical control devices and adapted to be mounted in a standard electrical wall box and employing the antenna to transmit to and receive signals from a local electrical control device which responds to the control signals from the master device.
Although the present invention is directed to an antenna for use in a lighting control system, the antenna of the present invention can be applied to the communication of signals relating to the control and status of other devices, for example, communication equipment, motors, security systems, appliances, HVAC systems (heating, ventilating and air conditioning).
The present invention is directed to an antenna of compact design which can be included within the lighting control device, for example, a light dimmer, and which fits into standard electrical wall boxes. The invention is also directed to the lighting control device itself, whether a master or local (remote) unit. The invention is of particular use in a system using radio frequency signals to control the status of lamps. In such a system, the conventional manually controlled hardwired lighting control devices, for example, wall switches and dimmers, are replaced by a dimmer having a control circuit and an antenna according to the present invention. The system in which the antenna according to the present invention is used is thus provided to enable an existing building lighting system (or other electrical/electronic devices) to be controlled remotely from various locations, without requiring hardwiring of the building to incorporate the necessary control system to accomplish remote control of lighting fixtures or other devices. Accordingly, in the system in which the antenna or lighting control device of the present invention is used, the lighting control device, e.g., a light dimmer which replaces a conventional light switch/dimmer, contains an antenna according to the present invention, the necessary actuators for accomplishing manual control of the light fixture, as well as a control circuit and RF circuit for allowing remote control via signals received and transmitted by the antenna of the lighting control device. The antenna and control device fit within a standard electrical wall box (or the antenna is sized so that it fits within the area defined by the faceplate of the wallbox), allowing the conventional lighting control device to be removed and replaced by the lighting control device according to the invention. Similarly, a master unit according to the invention having actuators thereon and an antenna for transmitting signals to the local control devices and receiving status signals from the local control devices is also adapted, according to one embodiment of the invention, to be disposed in a conventional electrical wall box. The antenna can be disposed completely or partly within the wallbox or it is sized so as to fit partly or completely outside the wall box at the wallbox opening but within the area defined by the faceplate of the wallbox.
In accordance with the present invention, the antenna is of compact size, fits within a standard electrical wall box or within the area defined by the faceplate of the wallbox and is a part of the electrical control device for controlling the lamp. The electrical control device also fits substantially within the standard electrical wall box.
There are various systems known in the prior art which allow for remote control of lamps without hardwiring control lines to the lighting control devices.
In one prior art system, a user can install a so called three-way electrical switch, i.e., an additional light control switch to an existing hardwired single control system by replacing an existing manually operated lighting control device with a lighting control device having a radio frequency receiver incorporated therein. The replacement lighting control device is hardwired into the electrical system in the same way as the conventional device to control the lamp. The radio frequency receiver is responsive to radio frequency signals generated by a remote battery powered switching device having a transmitter which can be conveniently affixed to a building wall at another location, thereby to provide the three-way switch circuit. The additional battery powered lighting control device has a manually operated lever, which when operated, sends an RF signal to the other electrical control device which is hardwired into the building's electrical system. The hardwired device will then toggle in response from its present state to the opposite state, i.e., from on to off or off to on. Thus, either switching device, the hardwired replacement or the battery powered device, can operate the lamp. Accordingly, a three-way electrical switch can be provided into an existing electrical system without hardwiring the three-way switch into the system.
In this prior art system, having the battery powered transmitting switch and the hardwired switch including a receiver, the hardwired receiving switch includes a whip antenna made from a piece of insulated wire which is allowed to dangle out of the electrical box either outside the building wall or inside the wall. In the case where the whip antenna is allowed to dangle outside the wall, an unattractive, aesthetically displeasing appearance is obtained. In the case where the whip antenna is allowed to dangle inside the wall, although hidden, the wire creates reception and installation problems as well as a danger that the wire may become shorted to other cables or grounds, presenting an electrical hazard or preventing the antenna from working.
In this prior art system, the battery powered transmitter generally includes a printed circuit board loop antenna. Another problem with this system is that the battery powered switch and hardwired switch must be located within a certain distance of each other in order for the system to operate.
In another prior art system, known as the X10 system, standard lighting control devices are replaced by lighting control devices operating via a power line carrier (PLC) communication system, i.e., information for operating the lighting control devices is provided over the building's existing power line by a power line carrier (PLC). In addition, in some of these systems, an RF communications link is also provided so that a hand-held remote control master device can be used to operate the various lighting control devices. In these systems, an RF repeater may also be provided. In the X10 system, only one-way communications is provided so that a master unit is not apprised by a lighting control device of the status of the controlled light fixtures.
In the X10 system, a radio frequency to PLC bridge is provided to convert radio frequency signals into power line carrier (PLC) communications signals. The RF to PLC bridge plugs into an existing wall outlet and provides the PLC carrier onto the electrical power line to be received by the controlled lighting control device. The antenna of the RF to PLC bridge is also, as in the case of the three-way switch described above, visible. Typically, the RF to PLC bridge comprises a box which is plugged into an existing wall electrical outlet, and has an antenna for receiving signals from the master controller or a repeater.
In addition to the X10 system, there are also known two-way communications links for providing, in general, home automation. These include the Electronic Industries Association Consumer Electronics Bus (CEBus) (EIAIS-60) protocols for radio frequency media, power line carrier media, infrared media and twisted pair media, and the Echelon Corporation LONworks. Intellon Corporation provides transceivers that comply with the CEBus standards for radio frequency and power line carrier. Echelon provides transceivers that comply with their communication protocol. None of these radio frequency transceivers package easily within the allowed area of a device as described by NEMA standards that fit in an electrical wallbox.
In addition to the above, a system known as the Smart House supplied by Smart House LP is also available. This system comprises a wired system and, accordingly, would entail expensive alteration and dislocation if applied to the control of electrical devices, particularly lighting in a home.
In addition to the above, the assignee of the present application offers systems known as HomeWorks, NetWorks and LuMaster which are hard-wired control systems controlling lighting devices. Although these systems are suitable for new construction, they entail major alteration and dislocation when applied to existing homes.
Also becoming available are wireless local area networks (LANs) for computer systems, which employ radio frequency communication methods ensuring that all nodes of the network can communicate with each other. See, for example, Electronic Design, Jun. 26, 1995, page 55.